A wind turbine known in the art comprises a tapered wind turbine tower and a wind turbine nacelle positioned on top of the tower. A wind turbine rotor with a number of wind turbine blades is connected to the nacelle through a low speed shaft, which extends out of the nacelle front as illustrated on FIG. 1.
As large modern wind turbines gets bigger and bigger both in size and in power output the challenge of transferring the torque through the drive train of the wind turbine i.e. from the rotor to the generator becomes more pronounced.
The drive train typically comprises several interconnected drive train components such as the rotor, a main shaft, one or more gearboxes, a brake system, an overload protection system and a generator where the different drive train components are interconnected by means of some sort of detachable or dismountable coupling enabling that the torque can be transferred in and between the components and at the same time enabling that the individual drive train components can be dismounted and/or replaced.
A known way of providing a coupling in the drive train is to use a so-called shrink-disk. The shrink-disc functions by converting locking screw clamp loads into radial contact pressures applied to the shafts of the mounted components, in effect “shrinking” it onto the shafts. Ideally this type of coupling will result in a zero-backlash mechanical interference fit, however wide friction joints (as required for large torque transfer) are sensitive to shaft bending and rotating loads, which may cause micro-slip and subsequently fretting or fretting corrosion. Furthermore when the torque exceeds the capacity of the joint, the coupling may slip and locally weld together. Once this happens, the coupling is very hard to remove again and removal will typically destroy one or both of the joined shafts.
From European patent application EP 1 445 484 A1 it is also known to provide a wind turbine with a friction coupling which by means of bolts creates a clamping force on the radial extending surfaces of one or more discs. However this type of coupling is complex and difficult to dismount.
An object of the invention is therefore to provide the drive train of a wind turbine with an advantageous torque transferring coupling technique.